WordPress 6.9 brought significant improvements to the block editor and overall performance, but it also introduced a series of incompatibilities that affected thousands of sites - from WooCommerce conflicts to broken plugins and performance issues on shared servers. This guide documents the most common problems and the solutions tested by our team across over 30 updated sites.
WooCommerce Incompatibilities
The conflict between WordPress 6.9 and WooCommerce was the most reported issue after launch - the checkout broke on WooCommerce versions prior to 9.5, and some payment gateways stopped working entirely.
Issue: Checkout Block Broken
WordPress 6.9 changed the way interactive blocks are rendered. The WooCommerce Checkout Block and Cart Block use React Server Components for hydration, and the changes in WordPress 6.9 introduced a conflict in the script loading order.
Symptoms:
Hydration failed or Cannot read properties of undefinedSolution:
Issue: Incompatible Payment Gateways
Stripe, Netopia, and other gateways that use the woocommerce_checkout_process hook experienced conflicts with the new validation flow in WooCommerce 9.4+.
Solution:
Performance Issues
WordPress 6.9 introduced a noticeable performance overhead on shared hosting servers - pages load 200-500ms slower due to the new Interactivity APIs loading on all pages, not just those that use them.
Issue: Interactivity API Loaded Everywhere
The new Interactivity API loads on every page, even if the page contains no interactive blocks. This adds approximately 80KB of JavaScript and 2-3 additional HTTP requests.
Solution:
Add the following to functions.php or a mu-plugin:
add_action('wp_enqueue_scripts', function() {
if (!is_admin()) {
wp_dequeue_script('wp-interactivity');
wp_dequeue_script('wp-interactivity-router');
}
}, 100);
Warning: Only disable this if you are not using interactive blocks (Query Loop with AJAX pagination, Search block, Navigation block). Test thoroughly after applying.
Issue: Increased Memory Usage
WordPress 6.9 consumes 15-25% more PHP memory per request, which on shared hosting with a 128MB or 256MB limit can cause Fatal error: Allowed memory size exhausted errors.
Solution:
wp-config.php: define('WP_MEMORY_LIMIT', '512M');Having issues with WordPress 6.9? Our team provides professional technical support and maintenance.
Conflicts with Popular Plugins
Several popular plugins had incompatibilities with WordPress 6.9 - here are the most common ones and the status of available fixes.
Elementor
Issue: The Elementor editor fails to load or loads partially. Custom widgets display errors.
Status: Fixed in Elementor 3.28+. Update Elementor before WordPress, not the other way around.
ACF (Advanced Custom Fields)
Issue: ACF fields in Gutenberg do not save correctly. ACF blocks display raw JSON instead of rendering properly.
Status: Fixed in ACF 6.4+. If you are using ACF Free, update through wp.org. ACF Pro - update from the Delicious Brains dashboard.
WPML
Issue: Page translations with blocks are lost or duplicated on save.
Status: Partially fixed in WPML 4.7.2. Residual issues with custom blocks require WPML 4.7.3+.
Yoast SEO / RankMath
Issue: The SEO analysis in the editor does not update in real time. The word counter displays 0.
Status: Fixed in Yoast 24.2+ and RankMath 1.0.235+.
Cache Plugins
Issue: WP Rocket, LiteSpeed Cache, and W3 Total Cache may serve stale pages or cause 500 errors after the update.
Solution: Completely flush all caches (including page cache, object cache, and opcode cache) immediately after updating to WordPress 6.9.
How to Properly Update to WordPress 6.9
The correct update process for WordPress 6.9 starts with preparing a staging environment and ends with a thorough verification of critical functionality - never directly on production.
Pre-Update Checklist
Staging Update Process
Production Update Process
Rollback - When and How
If something breaks on production:
Maximum acceptable time for diagnosing on production: 15 minutes. If you have not resolved the issue within 15 minutes, restore the backup. The entire process - staging, backup, rollback - is part of a professional WordPress maintenance plan that eliminates the risk of failed updates.
WordPress 6.9 - Is the Update Worth It?
Updating to WordPress 6.9 is worthwhile, but not immediately at launch - the recommendation is to wait for the first patch release (6.9.1 or 6.9.2) that addresses the critical bugs reported by the community.
Reasons to Update
Reasons to Wait
Frequently Asked Questions
Is it safe to update to WordPress 6.9?
Yes, if you follow the correct process: full backup, staging testing, update plugins before core, post-update verification. We recommend waiting for version 6.9.2+ for maximum stability.
Is WordPress 6.9 compatible with WooCommerce?
Yes, but it requires WooCommerce 9.5 or newer. Earlier WooCommerce versions have conflicts with the block checkout. Update WooCommerce before WordPress.
What should I do if my site broke after the update?
Restore the pre-update backup immediately (do not spend more than 15 minutes diagnosing on production). Then investigate on staging. If you do not have a backup, contact your hosting provider - most keep daily backups for 7-14 days.
How do I disable a plugin due to a conflict without admin access?
Connect via FTP or File Manager and rename the plugin directory from wp-content/plugins/plugin-name to wp-content/plugins/plugin-name-disabled. WordPress will deactivate it automatically.
Does WordPress 6.9 work on PHP 7.4?
WordPress 6.9 runs on PHP 7.4, but it is not recommended. PHP 7.4 has not received security patches since November 2022. The minimum recommendation is PHP 8.1, ideally PHP 8.2 or 8.3.
WordPress updates should not be a source of stress. Contact us for professional maintenance - we handle updates, testing, and rollback so you can focus on your business.
